As the original creator of the bootable backup solution, it's a homecoming for me every year to revisit the External Boot functionality on Apple's latest OS. As in years past, we're making it work, but again, macOS changes are putting up some hurdles. Who knew it was so much easier to just run around the hurdles?! This year, we're crossing the finish line with some flair.

Bootable copies not showing up in Startup Disk – Big Sur bug redux?

I remember seeing this one way back in Big Sur; you'd create a perfectly functional bootable copy of the system, but it wouldn't show up in the Startup Disk Preference Pane. Apple ultimately resolved that issue in macOS Monterey, but now we're seeing it again — unfixed in the Golden Gate release candidate. This time it's a little bit worse, because the workaround to choose the volume via the Startup Manager wasn't working (e.g. boot while holding the Power button). With a lot of in-depth research, I finally figured out what Apple's ASR utility wasn't doing, and now CCC handles that last little detail too. So once again, bootable copies made with CCC 7.2 will appear in both the Startup Disk app, and in the Startup Manager, no Terminal commands or reduced boot security required — always at the ready for those folks that depend on External Boot for hardware redundancy.

Now some flair: Incrementally-updated, bootable backups with backup versioning

Previously, once a CCC task was configured to create a bootable copy of the source, every future run of that task would erase the destination and reclone the entire source. That behavior was intentional, that's how we can make the most reliably-bootable copy of the system. But, that was also the biggest compromise to incorporating bootability into a backup strategy — it completely discards all backup history, you have to manually re-enable FileVault encryption on the backup, you lose all insight into what's changing on your Mac on a daily basis, and it takes a lot longer than an incremental update.

CCC 7.2 introduces a hybrid approach for bootable backups: as long as the source and backup OS versions are the same, CCC will update the backup incrementally without requiring any task configuration changes. This new approach will make many of the CCC-specific features available for bootable backup tasks, e.g. backup versioning, Quick Update, insight into what changes were made to the source between events. For the long stretches of time where your Mac's OS isn't getting updated every day, now you can enjoy the full benefits of the CCC backup solution.

These are great benefits for anyone that requires a bootable backup, but this isn't a panacea. If the OS versions don't match, the destination (and all backup versions) still must be erased and recloned; again, to offer the most reliably-bootable copy of macOS. We made improvements here, too. By default, CCC will ask for your approval before erasing the destination — this allows you to schedule your backup task without the fear of the backup getting automatically erased whenever the source OS is updated. That also allows you to retain the option of downgrading the source volume's macOS, which you might want a day or so to assess. When you're ready to update the backup's macOS, simply click the "Update macOS" button and CCC will recreate a new, bootable copy of the source.

How do I create a bootable backup with CCC?

CCC's Backup Volume Setup Assistant will offer to create a bootable backup of your source whenever you select a destination. If you want to convert your current backup into a bootable backup, click on CCC's Destination selector and choose Backup Volume Setup Assistant…, then select the option to create a bootable copy of the system.

Is a bootable backup right for me?

Whether a bootable backup is right for you boils down to whether you're building a backup strategy or a redundancy strategy. With a bootable backup, you can boot from an external device and immediately get back to work, without having to restore or migrate your data first — that's unparalleled redundancy. For someone that depends on their Mac for a stage performance, for example, having this level of redundancy is imperative protection against hardware or system problems. In cases like that, redundancy outweighs the benefit of backup-specific features like backup versioning, auditing, and incremental updates, so the periodic wiping of the backup is acceptable.

The average user may not see much benefit in that level of redundancy. Recovery via Migration Assistant to a clean installation of macOS is usually simpler for most people, fast enough for most people, and it's really the only game in town for migrating data to a new Mac. For those folks, the simpler logistics of a "Standard Backup" are the better choice, and that's why CCC still leads with a "Standard Backup" recommendation by default in its Backup Volume Setup Assistant.

We'll support whichever strategy you need

As I wrote back in May 2021, "CCC can make bootable copies of the system on Intel and Apple Silicon Macs right now, and we'll continue to support that functionality as long as macOS supports it." Five years later, I'll reassert that same claim — we'll support this functionality as long as macOS supports it. macOS may spring up some hurdles to making bootable copies of the system, but we're always committed to finding ways to keep it working.